This invention concerns wind turbines and more particularly a wind turbine having a series of sails or vanes radially arranged about a central axle for rotation about a vertical axis. Such devices have been heretofore described in the prior art. The essential arrangement comprises a series of vanes which are configured to catch the wind while moving with the wind so as to drive the central axle, but are faired to present a much reduced or eliminated reaction surface when rotating toward the wind direction. This imparts a net momentum acting on the central axle tending to rotate the axle in a single direction. The wind energy is thus converted to mechanical energy, which may be used to drive a utilization device such as a pump or an electrical generator.
Such vertical axis wind turbines have for the most part involved complex mechanisms to cyclically reconfigure or reorient the vanes to a wind catching and a wind reacting shape or orientation as the vane rotates about the central axis. Such mechanisms add cost and complexity to the device, and further require maintenance and the mechanism also reduces the available output power of the device, since these mechanisms require work to be operated due to frictional losses, etc.
The object of the present invention is to provide such a vertical axis wind turbine which is extremely simple and does not require significant maintenance but which yields a high power output from an input of wind energy.
Other such devices have been developed which a simpler opening and closing action of the vane is contrived to catch the wind in one direction and to fold together in the other direction. It is necessary for such simpler devices also to operate efficiently such as to maximize the wind energy conversion in order to enhance the net output of the device.
Accordingly, it is another object of the present invention to provide a simple, vertical axis wind turbine in which an effective opening action to the wind reactive configuration of the vane is provided so as to provide a high efficiency device which operates reliably in various wind conditions.
A further problem with all wind energy conversion devices is the capability of operating in a wide range of wind conditions from fairly light breezes to gale force winds without destroying or damaging the device, particularly at higher wind speeds.
It is still another object of the present invention to provide such a wind energy conversion device which can be operated across an extreme range of wind speeds without danger of destruction or damage to the components of the device.